What is biodiversity?

Biodiversity refers to the variety of life in all its forms, including the variety of organisms within an ecosystem. This encompasses not only the number of different species but also the diversity of genetic variation among individuals of those species, as well as the diversity of ecosystems themselves. Therefore, the correct answer highlights the concept that biodiversity is fundamentally about the different types of organisms present in a specific environment and how they interact with each other and their surroundings.

While the number of ecosystems in a region, genetic variation within a species, and the types of climates in various regions are all important aspects of the biological and environmental sciences, they do not capture the full scope of what biodiversity encompasses. Biodiversity is primarily concerned with the multitude of life forms and their interactions, making the recognition of the variety of organisms in an ecosystem the most fitting definition.